The heaviest single measure isn't how close two drivers are, it's how unpredictable the fight is. Whoever finishes three seconds behind you every single race is a benchmark, not a rival - so Head to head scores highest when neither driver reliably beats the other, and falls to nothing when one of them owns the pairing.

Finish gap is how near each other they take the flag, Wheel to wheel the share of laps they crossed the line within 2 seconds of each other - read from the telemetry recorded with a race, so races saved without telemetry don't count towards it - and Standings how close they stay on points, measured against the field's own spread.

Race pace (average clean race lap, from telemetry) and One-lap pace (best lap in qualifying or a race) compare the two drivers directly, at the same track in the same class only: PMR has no published benchmark to put different cars on one scale.

Same class is the share of their races together run in the same class. It isn't a filter, but it carries real weight: two drivers in different classes can never finish ahead of each other in a table that counts.

Only PMR races count, and only ones an admin has saved to a series with a scoring scheme. Practices and Lap Analysis sessions don't. The score is scaled down while there are few races to go on - which is why an early-season rival is marked provisional.